Metabolic changes in summer active and anuric hibernating free-ranging brown bears (ursus arctos)

The brown bear (Ursus arctos) hibernates for 5 to 6 months each winter and during this time ingests no food or water and remains anuric and inactive. Despite these extreme conditions, bears do not develop azotemia and preserve their muscle and bone strength. To date most renal studies have been limited to small numbers of bears, often in captive environments. Sixteen free-ranging bears were darted and had blood drawn both during hibernation in winter and summer. Samples were collected for measurement of creatinine and urea, markers of inflammation, the calcium-phosphate axis, and nutritional parameters including amino acids. In winter the bear serum creatinine increased 2.5 fold despite a 2-fold decrease in urea, indicating a remarkable ability to recycle urea nitrogen during hibernation. During hibernation serum calcium remained constant despite a decrease in serum phosphate and a rise in FGF23 levels. Despite prolonged inactivity and reduced renal function, inflammation does not ensue and bears seem to have enhanced antioxidant defense mechanisms during hibernation. Nutrition parameters showed high fat stores, preserved amino acids and mild hyperglycemia during hibernation. While total, essential, non-essential and branched chain amino acids concentrations do not change during hibernation anorexia, changes in individual amino acids ornithine, citrulline and arginine indicate an active, although reduced urea cycle and nitrogen recycling to proteins. Serum uric acid and serum fructose levels were elevated in summer and changes between seasons were positively correlated. Further studies to understand how bears can prevent the development of uremia despite minimal renal function during hibernation could provide new therapeutic avenues for the treatment of human kidney disease

Air Traffic Flow Management Under Emission Policies: Analyzing the Impact of Sustainable Aviation Fuel and Different Carbon Prices

As part of the global efforts to make aviation activities more environmentally friendly, the worldwide goal is to achieve a 50% reduction in the 2005 emissions by 2050. In this context, aviation emissions represent a critical challenge to aviation activities, especially with the increasing travel demand up to the beginning of the COVID-19 crisis, starting in 2020. One of the potential drivers that would help the aviation industry reduce its emissions is the use of sustainable aviation fuel (SAF). In this study, we analyzed the impact of SAF from an air traffic flow management (ATFM) perspective, considering delay and re-routing costs. We developed an optimization model that considers, in addition to the traditional ATFM costs, fuel costs and carbon dioxide emissions. We investigated the impact of accounting for these two new aspects, that is, fuel costs and emissions, on ATFM performance, and we compared SAF with conventional fuel. The analysis of a real case study revealed that, in addition to delay and re-routing costs, fuel cost should be included in the ATFM model so that the resulting solution becomes economically and environmentally realistic for airlines. The increase in the fuel cost and network delays when using SAF requires setting an appropriate carbon price under an emission policy, such as the carbon offsetting and reduction scheme for international flights policy, to make SAF more attractive. Furthermore, flexible re-routing programs for flights operated using SAF make it advantageous from an ATFM perspective

Central authority controlled air traffic flow management: An optimization approach.

Despite various planning efforts, airspace capacity can sometimes be exceeded, typically due to disruptive events. Air traffic flow management (ATFM) is the process of managing flights in this situation. In this paper, we present an ATFM model that accounts for different rerouting options (path rerouting and diversion) and pre-existing en-route flights. The model proposes having a central authority to control all decisions, which is then compared with current practice. We also consider inter-flight and inter-airline fairness measures in the network. We use an exact approach to solve small-to-medium-sized instances, and we propose a modified fix-and-relax heuristic to solve large-sized instances. Allowing a central authority to control all decisions increases network efficiency compared to the case where the ATFM authority and airlines control decisions independently. Our experiments show that including different rerouting options in ATFM can help reduce delays by up to 8% and cancellations by up to 23%. Moreover, ground delay cost has much more impact on network decisions than air delay cost, and network decisions are insensitive to changes in diversion cost. Furthermore, the analysis of the trade-off between total network cost and overtaking cost shows that adding costs for overtaking can significantly improve fairness at only a small increase in total system cost. A balanced total cost per flight among airlines can be achieved at a small increase in the network cost (0.2 to 3.0%) when imposing airline fairness. In conclusion, the comprehensiveness of the model makes it useful for analyzing a wide range of alternatives for efficient ATF

Pricing of ice hockey tickets : Supply, demand, monopoly and new arenas

This thesis is about pricing of ice hockey tickets in Swedish ice hockey. Ice hockey is a large sport in Sweden, with clubs that more and more are acting like companies. These clubs tend to build new arenas that in many ways change basic variables. The thesis is an analytic thesis based on information about the clubs and interviews. The purpose is to study the basic variables for pricing of tickets in Swedish ice hockey. Furthermore the pricing itself and its connection to the new arenas are studied. The focus of the thesis is on the three clubs HV 71, Färjestads BK and Linköpings HC. Theses three clubs come from relatively large Swedish cities and have recently built arenas. The thesis only concerns the clubs’ profit maximization of selling tickets to the public. Five conclusions are drawn: 1) The supply consists of ice hockey, but also more than that. 2) The demand is large and can be divided into several demand curves that together form stairs. 3) The clubs have monopoly in their respective region. 4) The new arenas have changed supply and demand in a way that the price level has raised. 5) The clubs’ pricing differ in quality.Denna uppsats behandlar prissättning av biljetter inom svensk ishockey. Ishockey är i Sverige en stor idrott med elitföreningar som allt mer drivs som företag. Allt fler av dessa föreningar bygger nya moderna arenor som på flera olika sätt för med sig förändrade förutsättningar. Uppsatsen bedrivs i form av positiv ekonomisk analys med information om föreningarna och intervjuer som underlag. Syftet med denna uppsats är att studera förutsättningarna för prissättningen av biljetter inom svensk ishockey. Dessutom studeras själva prissättningen och dess samband med de nya arenorna. I uppsatsen studeras HV 71, Färjestads BK och Linköpings HC. Dessa tre föreningar hör hemma i relativt stora svenska städer och har nybyggda arenor. Uppsatsen fokuserar på föreningarnas vinstmaximering gentemot publik i form av privatpersoner. Fem slutsatser dras i uppsatsen: 1) Utbudet består av ishockey, men också av mycket annat. 2) Efterfrågan är stor och kan indelas i flera efterfrågekurvor som tillsammans tar formen av en trappa. 3) Föreningarna har monopolställning i respektive region. 4) De nya arenorna har förändrat utbud och efterfrågan så att priserna har ökat. 5) De olika föreningarna prissätter olika bra

Fysisk aktivitet och självupplevd stress

Idag utsätter vi våra kroppar för ett stresspåslag som vi inte är skapta att klara av, kronisk stress. Stress kan vara en positiv faktor när vi ska prestera, men när kraven blir för höga får kroppen ingen återhämtning vilket kan orsaka både fysisk- och psykisk skada. Syftet med studien var att undersöka om det fanns något förhållande mellan upplevd stressnivå och nivån av fysisk aktivitet hos vuxna. Alla deltagare bar en plomberad pedometer under fyra dygn, antal steg lästes av den fjärde dagen av undersökningsledaren. Enkäten Depression, Anxiety and Stress Scale (DASS) användes i en svensk förkortad översättning. Resultatet visar att de som når rekommendationen på 10 000 steg/dag har svårare att tolerera avbrott i saker de håller på med. Deltagarna från gruppen butiksarbete rör sig även mer än studenterna, som i sin tur rör sig mer än de med administrativ tjänst. Butiksarbetarna är även de enda av de tre arbetsplatserna som når upp till rekommendationen för steg/dag. Någon skillnad i stress i förhållande till fysisk aktivitet (steg) gick inte att hitta mellan de tre arbetsplatserna. Frånvaron av förmåga att koppla av visade sig ha en tendens till att vara en stressfaktor på alla arbetsplatser och insatser borde göras för att reda ut vad som orsakar detta

Inventering, analys och värdering av olycksrisker ur miljö-, hälso- och PR-perspektiv - En fallstudie på Stockholm-Arlanda Airport

This Master’s thesis presents a model that can be used to assess the public reactions and coverage in the media following an environmental accident. A risk assessment focusing on risks for the environment and human health is done in a case study at Stockholm-Arlanda Airport, and the results from this study is used to test the model for assessment of PR-damage suggested by the authors to this master thesis. The results from the study implies that the operations at Stockholm- Arlanda Airport give rise to several risks for the environment and human health, and also that the suggested model for PR-assessment should be further evaluated before it can be used to effectively assess negative PR-effects for organizations

Air traffic flow management under emission policies: Analyzing the impact of sustainable aviation fuel and different carbon prices

International audienc

Central Authority-Controlled Air Traffic Flow Management: An Optimization Approach

Despite various planning efforts, airspace capacity can sometimes be exceeded, typically because of disruptive events. Air traffic flow management (ATFM) is the process of managing flights in this situation. In this paper, we present an ATFM model that accounts for different rerouting options (path rerouting and diversion) and preexisting en route flights. The model proposes having a central authority to control all decisions, which is then compared with current practice. We also consider interflight and interairline fairness measures in the network. We use an exact approach to solve small- to medium-sized instances, and we propose a modified fix-and-relax heuristic to solve large-sized instances. Allowing a central authority to control all decisions increases network efficiency compared with the case where the ATFM authority and airlines control decisions independently. Our experiments show that including different rerouting options in ATFM can help reduce delays by up to 8% and cancellations by up to 23%. Moreover, ground delay cost has much more impact on network decisions than air delay cost, and network decisions are insensitive to changes in diversion cost. Furthermore, the analysis of the tradeoff between total network cost and overtaking cost shows that adding costs for overtaking can significantly improve fairness at only a small increase in total system cost. A balanced total cost per flight among airlines can be achieved at a small increase in the network cost (0.2%-3.0%) when imposing airline fairness. In conclusion, the comprehensiveness of the model makes it useful for analyzing a wide range of alternatives for efficient ATFM.Funding Agencies|University of Sharjah, Sharjah, United Arab Emirates [1702040585]; VINNOVA, the Swedish innovation agencyVinnova [2018-02998]</p

Central authority controlled air traffic flow management: An optimization approach

Despite various planning efforts, airspace capacity can sometimes be exceeded, typically because of disruptive events. Air traffic flow management (ATFM) is the process of managing flights in this situation. In this paper, we present an ATFM model that accounts for different rerouting options (path rerouting and diversion) and preexisting en route flights. The model proposes having a central authority to control all decisions, which is then compared with current practice. We also consider interflight and interairline fairness measures in the network. We use an exact approach to solve small- to medium-sized instances, and we propose a modified fix-and-relax heuristic to solve large-sized instances. Allowing a central authority to control all decisions increases network efficiency compared with the case where the ATFM authority and airlines control decisions independently. Our experiments show that including different rerouting options in ATFM can help reduce delays by up to 8% and cancellations by up to 23%. Moreover, ground delay cost has much more impact on network decisions than air delay cost, and network decisions are insensitive to changes in diversion cost. Furthermore, the analysis of the tradeoff between total network cost and overtaking cost shows that adding costs for overtaking can significantly improve fairness at only a small increase in total system cost. A balanced total cost per flight among airlines can be achieved at a small increase in the network cost (0.2%-3.0%) when imposing airline fairness. In conclusion, the comprehensiveness of the model makes it useful for analyzing a wide range of alternatives for efficient ATFM.Funding Agencies|University of Sharjah, Sharjah, United Arab Emirates [1702040585]; VINNOVA, the Swedish innovation agencyVinnova [2018-02998]</p